21 March 2017

Difference between thermoplastic and thermosetting plastic

What is Thermoplastics?

A thermoplastic is a polymeric material which softens when heated and hardens upon cooling.

What is Thermosetting plastics?

Thermosetting plastic is a polymeric material, which once having cured or hardened by a chemical reactions does not soften or melt upon subsequent heating.

Thermoplastic and thermosetting are both two different classes of polymers, which are differentiated based on their behaviour in the presence of heat.  

Main difference : 

The main difference is thermoplastic materials have low melting points, therefore they can be remoulded or recycled by exposing it to heat whereas thermosetting plastic can withstand high temperatures without losing its rigidity, therefore they cannot be reformed, remoulded or recycled by applying heat. 

Let us have a deep insight into the difference between thermoplastic and thermosetting plastic. 

Difference between thermoplastic and thermosetting plastic :

  • Thermoplastic softens with heat while not softens with the heat in case of the thermosetting plastic.
  • A thermoplastic material has a linear polymer chain while a thermosetting plastic material consists of a cross-linked polymer chain.
  • A thermoplastic is 2 dimensional with no crosslinks whereas thermosetting plastic is 3 dimensional with multiple cross-links. 

Thermoplastic and Thermosetting plastic

  • The thermoplastic material can be softened, hardened or softened repeatedly by the application of heat while thermosetting plastic material once set and hardened it can't be remelted or reshaped.
  • The thermoplastic material can be recycled while not possible to recycle in the thermosetting plastic.
  • Thermoplastic components are environment-friendly while thermosetting plastic components after their useful life create a problem.
  • Thermoplastic materials are flexible because of molecules in the linear chain while thermosetting materials are more rigid because of molecules in cross-linked.
  • Thermoplastic is processed by injection moulding, extrusion process, blow moulding, thermoforming process and rotational moulding while thermosetting plastic is processed by compression moulding, reaction injection moulding.
  • Thermoplastic is synthesised by addition polymerization while thermosetting plastic is synthesised by condensation polymerization.
  • Thermoplastic is lower in molecular weight while thermosetting plastic is higher in molecular weight.
  • Thermoplastic can be reshaped and reused while thermosetting plastic can not.
Example of thermoplastic materials :
  • Polyethene
  • Polypropylene
  • Polyvinylchloride ( PVC )
  • Polystyrene
  • Polytetrafluoroethylene ( PTFE )
  • Nylon
Example of thermosetting plastic materials :
  • Aminos
  • Polyesters
  • Phenolics 
  • Epoxies 
  • Phenol-formaldehyde

Difference between physical properties :

  • Melting point is low in thermoplastic while high in a thermosetting plastic.
  • Tensile strength is low in thermoplastic while high in a thermosetting plastic.
  • Thermal stability is low in thermoplastic while high in a thermosetting plastic.
  • Stiffness and brittleness are low in thermoplastic while high in a thermosetting plastic.
  • Rigidity and durability are also low in thermoplastic while high in a thermosetting plastic.
  • Thermoplastic is soluble in some organic solvents while thermosetting plastic is insoluble in organic solvents.